Ejection unit for a satellite

ABSTRACT

The invention relates to an ejection unit for at least one satellite, in particular a picosatellite, comprising a frame that defines an inner space for receiving the satellite; and a retention device for holding the satellite in the inner space, the retention device being configured such that the satellite is releasable from the retention device.

The present invention relates to an ejection unit for at least onesatellite, in particular a picosatellite, having a frame that defines aninner space for receiving the satellite.

Picosatellites according to the CubeSat standard are, for example,typically transported into an orbit by a rocket and are ejected from therocket there by an ejection unit. In this respect, the satellite and theejection unit are exposed to high loads, in particular on the launch ofthe rocket and on the separation of rocket parts such as a larger mainsatellite.

It is an object of the invention to securely fix a satellite in anejection unit of the initially named kind during the transport to anejection site.

The object is satisfied by an ejection unit in accordance with claim 1and in particular in that the ejection unit comprises a retention devicefor holding the satellite in the inner space that is configured suchthat the satellite can be released from the retention device. Thesatellite can hereby be securely fixed in the ejection unit and can bereliably released and ejected at the ejection site.

In an embodiment, the retention device comprises a cover for closing theinner space, wherein the cover is releasably blocked with respect to theframe by at least one displaceable bolt in a closed position.

The use of the bolt represents a particularly simple, but reliablepossibility to block the cover with respect to the frame and thus to fixthe satellite during the transport. In addition, the cover and thus thesatellite can hereby be reliably released. A bolt can furthermore bedisplaced particularly precisely and at an exactly defined time torelease the cover. It is therefore ensured by the bolt that thesatellite can be ejected exactly at a planned ejection site.

The bolt grips into a blocking recess provide for the bolt in the closedposition of the cover, for example, and can be pulled out of theblocking recess to release the cover. The blocking recess can inparticular be part of the frame or can be fastened thereto.

In a further embodiment, the bolt is formed as a part of the cover. Thisallows a particularly compact construction of the ejection unit, inparticular of the frame, wherein a displacement mechanism for the boltcan in particular be completely accommodated in the cover.

The cover can, for example, be supported under a preload in the closedposition such that the cover is moved into an open position when it isreleased. No separate actuation system is thereby required to open thecover, which ensures a secure opening of the cover and likewise makespossible a compact construction of the ejection unit. The cover can, forexample, be pivoted open about a pivot axis and can be preloaded aboutthe pivot axis by a torsion spring. Alternatively or additionally, thecover can be resiliently supported with respect to the satellite suchthat the cover pushes off into the open position after the release fromthe satellite.

The ejection unit can in particular have a release mechanism by whichthe bolt can be moved out of a blocking position into a releaseposition. The release mechanism can in particular be provided with aredundancy. The release mechanism is, for example, formed as part of thecover, which allows a compact construction.

In a further development, the release mechanism comprises a slider thatis coupled to the bolt, that is held preloaded in a blocking positionand that is releasable from this position to displace the bolt into arelease position. The bolt is, for example, connected in an articulatedmanner to the slider by a linkage, wherein the slider and the linkagecan form an elbow joint for the bolt.

In a further embodiment, two bolts are provided. The cover can hereby beredundantly securely fixed, namely at two points. The bolts are in thisrespect in particular aligned such that they are displaceable in anopposed manner into a respective release position. The bolts are inparticular arranged coaxially.

For example, a or each bolt is preloaded in the direction of a releaseposition by a spring. In this respect, the bolts can be set force freein a blocking position by a linkage. It is hereby achieved that noforces act on further movable components, in particular of a releasemechanism, in the blocking position. The bolts are thus heldparticularly reliably in the blocking position and an unwanted releaseof the cover is effectively avoided. The bolts can in particular bealigned such that returning forces of the spring are substantiallybalanced. Alternatively or additionally, the bolts can be set force freeby the linkage in the blocking position such that a minimum deflectionof the linkage and/or of the bolts has the result that the bolts are nolonger set force free such that at least one of the springs displacesthe bolt or bolts into the release position. Such an embodiment provesadvantageous because a secure and force free support of the bolts ishereby ensured, on the one hand, and the springs can reliably effect therelease of the cover at the desired point in time, on the other hand.

In a further embodiment, each bolt can be connected to a slider of therelease mechanism via a separate linkage. In this respect, the linkageswith the slider form a double elbow joint that couples the bolts to theslider such that a movement of a bolt into the release position resultsin a movement of the second bolt into the release position. It isensured by such a coupling, in particular in a redundant manner, thatboth bolts are displaced into their release positions at a desiredrelease time. At least one spring for a bolt can in particular have suchlarge dimensions that it also effects a displacement of both bolts intothe release position on a failure of a further spring, wherein for thispurpose a minimum deflection of the linkage and/or of the bolts mayoptionally be necessary. Two of these springs that have such largedimensions are advantageously provided such that the bolts can bedisplaced redundantly, that is with a particularly high safeguardingagainst failure, into their respective release positions.

The release mechanism can comprise at least one rocker lever by whichthe at least one bolt is held indirectly or directly in a blockingposition. The rocker lever can in this respect in particular tilt out ofa blocking position to release the bolt. The bolt can, for example, beheld via a slider interposed between the rocker lever and the bolt. Therocker lever in particular has a first lever arm and a second lever arm,wherein the bolt in the blocking position is supported directly orindirectly at the first lever arm and an electrically controllableholding device is active at the second lever arm that releases thesecond lever arm by an electrical control such that a preloaded elementsuch as the bolt and/or a spring connected to the first lever end movesthe rocker lever into a release position.

A further embodiment is characterized in that two rocker levers areprovided and a preloaded element of the release mechanism comprises apivot arm that is in engagement with both rocker levers in the blockingposition to support the preloaded element, wherein the pivot arm ispivotable such that the preloaded element, and thus the bolt, arereleasable from the blocking position by tilting only one rocker leverinto a release position. This embodiment provides a redundant and thusparticularly reliable release of the cover. The preloaded element can inparticular comprise the bolt or bolts and/or a slider.

It is also advantageous if the at least one rocker lever has a pivotbearing and is loaded by a preloaded element of the release mechanismthat has a slope by which a force exerted onto the rocker lever by thepreloaded element extends in the direction of the pivot bearing, inparticular through an axis of rotation of the pivot bearing. The forceexerted on the rocker lever by the preloaded element in a blockingposition is hereby taken up, in particular substantially completely, bythe pivot bearing such that substantially no torque results on the leverfrom this force, at least in the blocking position. This has the resultthat the preloaded element also does not substantially effect any torqueon the rocker lever about its axis of rotation on high mechanical loadson the ejection unit, e.g. during a rocket launch, and the rocker levercan thus be held particularly securely in its blocking position duringthese loads.

The ejection unit in accordance with the invention can also be furtherimproved in that the bolt has a slope for a running onto a frame-sidecounter-bearing for the bolt in the blocking position. This prevents thebolt from sticking at the counter-bearing even though the bolt and/or arelease mechanism for the release has been actuated. Such a sticking canbe caused without the slope, for example, by galling and/or by shapechanges of the bolt and/or counter-bearing during high mechanical loads,e.g. during a rocket launch. The slope therefore has the effect that thebolt can be displaced into the release position with a particularly highreliability. The slope is in particular slanted with respect to a mainaxis of the bolt. The slope can e.g. be substantially planar or can alsohave a different, e.g. swept, shape.

The safety advantage of the slope is further amplified when thecounter-bearing is a ball bearing. In this case, the slope can also rolloff gently at the ball bearing under high loads so that shape changesand galling are avoided even more effectively. A ball bearing can,however, also be provided in a differently shaped, for examplecylindrical, bolt.

In a further embodiment, the bolt and the counter-bearing are preloadedagainst one another in an ejection direction in a blocking position. Thecounter-bearing thereby exerts a force in the direction of its releaseposition via the slope onto the bolt in the blocking position. Therelease of the cover is thus ensured even more reliably. The preload inparticular has such a large dimension that the force on the bolt islarge enough to move the bolt, and in particular also a second bolt,into the release position on its own, that is e.g. on a failure of aspring associated with the bolt. This embodiment also serves, inparticular in conjunction with further redundant measures, to ensure arelease of the cover at the desired time in every case.

In accordance with an advantageous further development, two bolts andtwo rocker levers of the release mechanism are arranged symmetricallywith respect to a slider of the release mechanism. It can hereby beensured that the bolts are simultaneously move into the release positionat the desired time.

Alternatively or additionally, a magnetic holder is provided by whichthe release mechanism is held magnetically in a secured position. Inthis respect, a magnetic field of the magnetic holder can in particularbe variable to move the release mechanism into a release position. Therelease mechanism can hereby be held in the blocking position withoutany energy input and only a relatively small energy input is required tomove the release mechanism into the release position. The magneticholder can in particular engage at a lever arm of a rocker lever.

In a further embodiment of the invention, the ejection unit defines anejection direction and the retention device comprises a fixing apparatusthat engages at the satellite transversely to the ejection direction forfixing the satellite, wherein the fixing apparatus has at least onemovable fixing element that is movable, in particular substantiallyexclusively, in a translatory manner between a fixing position and arelease position.

The satellite can in particular be effectively fixed by the fixingapparatus in at least one direction transversely to the ejectiondirection. The translatory movement of the fixing element effects aparticularly defined movement of the fixing element between the fixingposition and the release position. The satellite can thus be releasedprecisely at a desire time by the fixing apparatus. A fixing of thesatellite in the ejection direction can, for example, be effected by acover of the ejection unit or by a preloaded element arranged at thecover. Alternatively or additionally, the fixing by the fixing elementcan also effect a fixing in the ejection direction, e.g. by shapematching and/or friction locking. The fixing element can in particularbe movable transversely to the ejection direction and/or can bedisplaceable toward an outer wall of the satellite for the fixingthereof. The fixing apparatus is, for example, of elongate design and/orextends substantially in parallel with the ejection direction, whichallows a compact construction of the ejection unit.

In a further development, at least a pair of fixing elements is providedthat are effective in a plane that extends transversely to the ejectiondirection. The satellite can hereby be even more effectively fixed. Thefixing elements of the at least one pair in particular act substantiallyperpendicular to one another and/or at a corner of the satellite.

For an even more secure fixing, alternatively or additionally, aplurality of fixing elements or pairs of fixing elements can be providedthat are arranged distributed along the ejection direction. Thesatellite is hereby effectively protected against a tilting and is inparticular fixed over substantially its total length.

A spring element that tensions the or each fixing element in the fixingposition with respect to the satellite can in particular be provided forcompensating production tolerances.

In a further embodiment, the fixing apparatus can have a guide for thefixing element by which the fixing element is movable between the fixingposition and the release position. A particularly compact constructionof the fixing element and thus of the ejection device is hereby madepossible. The slot guide is in particular configured to effect atranslatory movement of an element of the fixing apparatus in parallelwith the ejection direction into a translatory movement of the fixingelement transversely to the ejection direction, in particular whereinthe element in one part displaces a plurality of separate fixingelements over respective slot guides.

The fixing element can, for example, be displaceably supported in a railfor the satellite and/or for a satellite platform. A rail for thesatellite and/or for a satellite platform is typically anyway providedin an ejection unit to be able to eject the satellite in a defineddirection without rotation. A guide for the fixing element can thusadvantageously be integrated into the rail, in particular into one offour rails of a satellite chamber, such that in turn a particularlycompact construction is made possible.

Provision can furthermore be made that the fixing apparatus is coupledto a cover of the ejection unit such that an opening of the covereffects a moving of the or each fixing element into the releaseposition. It can thus be ensured without an additional actuator systemthat the release of the satellite takes place at a specific openingangle of the cover. This specific opening angle amounts, for example, toapproximately 90°.

The fixing apparatus in a further development comprises at least twoelements that are displaceable relative to one another along theejection direction for fixing and/or releasing the satellite. Thisfurther development also makes possible a particularly compactconstruction. The displacement can, for example, be carried out inparallel with the ejection direction. One of the elements is inparticular the fixing element. Alternatively or additionally, one of theelements can, for example, have a guide projection and/or a guide bolt,in particular for engagement with a guide of another one of theelements.

Alternatively or additionally, one of the elements can be configured asa hollow section and a control bar can be provided for controlling thedisplacement of the element relative to the other element, the controlbar extending through the hollow section.

In accordance with a further embodiment of the invention, an ejectionspring blockable by a lever and a latch for locking the lever in ablocking position are provided. In this respect, the latch is coupled toa cover of the ejection unit with a floating support. This embodimenthas the advantage that a closing of the cover, for example by accident,does not result in damage to the lever when the lever is not located ina locking position, but rather in another undefined position that wouldhave the consequence of a collision of the latch with the lever on theclosing of the cover.

The latch can in particular be coupled to the cover via a spring, whichrepresents a particularly simple variant of the floating support. Thelatch can thus simply compress on a collision with the lever without thelever or other parts of the ejection unit being damaged.

A further independent subject of the invention that can, however, becombined with the above-described subjects is an ejection unit for atleast one satellite, in particular a picosatellite, having a frame thatdefines an inner space for receiving the satellite and an opening to theinner space, a covering for the opening releasably fastened to the frameby means of a fastening element and a security against loss for thefastening element.

It can, for example, be necessary briefly before the launch of a rockettransporting the satellite to release the covering from the frame, forexample to switch on electronics of the satellite through the opening.It is prevented by the security against loss that in this respect thefastening element is lost and in particular falls into an inaccessibleregion of the rocket, which would have the consequence that thefastening element would have to be looked for and removed before thelaunch.

The security against loss can, for example, be configured as a lug thatcan be restored and that is in particular fastened to the covering. Thesecurity against loss can preload the fastening element toward thecovering. The fastening element can be configured as a screw. The screwcan in particular comprise a screw head which has a projection, inparticular a peripheral projection, that projects radially with respectto a screw axis and via which the security against loss preloads thefastening element.

Further embodiments of the invention can be seen from the claims, fromthe description and from the drawings.

The invention will be explained only by way of example in the followingwith reference to schematic drawings.

FIG. 1 shows an ejection unit in accordance with the invention in aperspective view;

FIG. 2 shows a cover of the ejection unit with a release mechanism in arelease position in a plan view;

FIG. 3 shows a sectional view of the cover;

FIG. 4 shows a further plan view of the cover, with the releasemechanism being located in a blocking position;

FIG. 5 shows a bolt of the cover in a sectional view;

FIG. 6 shows an alternative embodiment of a cover of an ejection unit inaccordance with the invention;

FIG. 7 shows a fixing apparatus of the ejection unit of FIG. 1 in aperspective view;

FIG. 8 shows the fixing apparatus in a side view;

FIG. 9 shows the fixing apparatus in a further side view;

FIG. 10 shows the fixing apparatus and a rail for a satellite in aperspective view;

FIG. 11 shows the fixing apparatus and the rail in a further perspectiveview;

FIG. 12 shows a fixing element of the fixing apparatus in a perspectivesectional view;

FIG. 13 shows a securing mechanism for a satellite platform of theejection unit of FIG. 1 in a perspective view;

FIG. 14 shows a covering of the ejection unit of FIG. 1; and

FIG. 15 shows a side view of the covering.

The ejection unit 20 shown in FIG. 1 comprises a frame 22 that definesan inner space for receiving a plurality of satellites, not shown. Theinner space comprises four satellite chambers that can each be closed bya cover 30. Each cover 30 secures a satellite with respect to a movementin an ejection direction A in a closed position. In addition, a fixingapparatus 150 is arranged in each satellite chamber and secures thesatellite transversely to the ejection direction A.

The frame 22 comprises a plurality of openings for each satellitechamber that are each closed by a covering 250. An engineer can reachthe respective satellite through the openings without having to removeit from the ejection unit 20.

Each cover is rotatably supported about a cover axis 24 at one side andis preloaded into an open position by a cover spring 26 that isconfigured as a torsion spring. The cover 30 comprises a plurality ofdampening pins 90 that contact the respective satellite in the closedposition and secure it in the ejection direction A.

Each cover 30 is blocked in its closed position during the transport ofthe satellites to a desired ejection site and is released at theejection site, whereupon the cover is moved into its open position as aconsequence of the preload by the cover spring 26 such that therespective satellite can be ejected.

One and the same cover 30 is respectively shown in FIGS. 2 and 4 withouta covering 102 visible in FIG. 1 such that a release mechanism of thecover 30 is visible. In FIG. 2, the release mechanism is in a releaseposition in which the cover 30 can move into its open position. FIG. 4shows the release mechanism in a blocking position in which the cover 30is blocked in its closed position.

The cover 30 comprises two bolts 34 that project, as visible in FIG. 4,from a cover frame 32 of the cover 30 in opposite directions forblocking the cover 30 and that engage with the frame 22. Each bolt 34 ispreloaded by a bolt spring 36 via a securing ring 38 and a disk 40 intoa release position, namely in the direction of a cover interior. Thebolt spring 36 is supported at the cover frame 32 for this purpose.

Each bolt 34 has a bolt head 42 that is disposed opposite a blockingbolt end and forms a rotary joint with a limb 46 via a pivot pin 44. Thelimb 46 is likewise connected to an elbow element 48 of a slider 50rotatable about a pivot pin 47. The limb 46 and the elbow element 48form an elbow joint for the respective bolt 34.

The slider 59 is displaceably supported by a first slider bearing 58 andby a second slider bearing 60 in a direction perpendicular to the bolt34, vertically in FIG. 2. The slider bearings 58, 60 are fixed to thecover frame 32 via screws 62. The slider 50 is preloaded by two slidersprings 54 in the direction of a release position. The slider springs 54are each guided on a spring guiding pin 56.

The slider 50 comprises a pivot arm 52 that is rotatably connected to abody of the slider 50 via a pivot pin 51. The pivot arm 52 comprises atan end disposed opposite the pivot pin 51 two slopes 53 at which thepivot arm 52 and thus the slider 50 are supported in a blockingposition.

The release mechanism additionally comprises two rocker levers 64 thatare each rotatably supported by lever bearing pin 72. Each lever 64 hasa first lever arm at whose end a ball bearing 68 is provided forengagement with one of the slopes 53 of the pivot arm 52 in the blockingposition. The ball bearing 68 is connected to the first lever arm via apin 66. A lever spring 70 is additionally active at the first lever armand preloads the rocker lever 64 into a release position. A second leverarm of the rocker lever 64 disposed opposite the first lever armcomprises a rotational pin 76 via which a magnetic plate 74 is rotatablyconnected to the second lever arm of the rocker lever 64. The magneticplate 74 does not necessarily have its own permanent magnetic field, butcan rather be magnetically acted on by a force.

An electric permanent magnet 78 that is fixed to the cover frame 32 viaa screw 82 is provided to attract the magnetic plate 74 and thus to holdthe rocker lever 64 against a preload force of the lever spring 70 intothe blocking position. The electric permanent magnet 78 has a permanentmagnetic field that is electrically variable to release the cover 30. Acircuit board 84 that is likewise fixed to the cover frame 32 by a screw86 is provided to vary the magnetic field. A cable conduit 88 from thecircuit board 84 to a control unit, not shown, is indicated by an arrow.

The function of the release mechanism of the cover 30 will be describedin more detail in the following. FIG. 4 shows the release mechanism inits blocking position and FIG. 2 shows the release mechanism in itsrelease position.

When, starting from the blocking position in accordance with FIG. 4, arelease command is output to the circuit boards 84 by the controldevice, a respective circuit board 84 generates an electrical impulsethat briefly attenuates the permanent magnetic field of the associatedelectric permanent magnet 78 The permanent magnetic field is in thisrespect attenuated at least so much that the associated lever spring 70moves the associated rocker lever 64 into its release position and in sodoing releases the magnetic plate 74 from the electric permanent magnet78.

The release command of the control device is simultaneously transmittedto both circuit boards 84. Both rocker levers 64 are therefore movedsubstantially simultaneously into the release position. The two leverarms are in engagement with an abutment 80 in the release position.

In the blocking position, both rocker levers 64 support the pivot arm 52and thus the slider 50. If now the rocker levers 64 are moved into therelease position, the pivot arm 52, and thus the slider 50, are nolonger supported in this blocking position, but are rather released intothe release position, namely vertically downwardly in FIGS. 2 and 4.

The associated lever springs 70 and the associated electric permanentmagnets 78 of the rocker levers 64 are each arranged symmetrically withrespect to a displacement axis of the slider 50. If one of the rockerlevers 64 is not moved into its release position in response to therelease command of the control device, for example because theassociated circuit board 84 is defective, the slider 50 is neverthelessdisplaced into the release position. For in this case, the pivot arm 52slides off at the ball bearing 68 of the rocker lever 64 that hasremained in the blocking position and is pivoted with respect to theslider body so that the slider 50 can slide into its release position.The symmetrically arranged rocker levers 64 therefore in particular forma redundant mechanism in conjunction with the pivot arm 52 to releasethe slider 50 into its release position. This mechanism also ensures arelease when one of the rocker levers 64 defectively remains in itsblocking position.

In the blocking position of FIG. 4, the pivot arm 52 is supported at itsend-side slopes 53 at the respective first lever arms of the rockerlevers 64 such that forces exerted on the rocker levers 64 by the slider50 or by the pivot arm 52 extend through a respective axis of rotationof the rocker levers 64 that is defined by the lever bearing pin 72. Itis hereby ensured that these forces are completely received by the leverbearing pins 72 and do not result in a torque on the rocker lever 64about the lever bearing pin 72. This ensures that the magnetic plate 74also does not release from the electric permanent magnet 78 in anunwanted manner under high loads of the ejection unit 20.

In the blocking position, the elbow element 48 is positionedsubstantially exactly between the bolts 34 and the limbs 46 are in thisrespect aligned in parallel with the bolts 34. In this position, thespring forces of the bolt springs 36 act in opposite directions andbalance in the elbow element 48. In the blocking position, the boltsprings 36 therefore substantially do not exert any force on the slider50 in the direction of its displacement axis. This arrangement alsominimizes forces exerted on the slider 50 under high loads, inparticular during the transport of the satellite in a rocket. Thisarrangement also contributes to the fact that the release mechanism isnot moved into the release position at an unwanted time and thusreleases the cover in an unwanted manner.

As soon as at least one of the rocker levers 64 pivots into its releaseposition, the slider 50 is therefore displaced, vertically downwardly inFIG. 4, by the slider spring 54 out of its blocking position in thedirection of its release position. The slider spring 54 has relativelysmall dimensions, in particular in comparison with the bolt springs 36,and substantially only serves to deflect the elbow element 48 minimallyso that the spring forces of the bolt springs 36 no longer mutuallybalance, but rather displace the slider 50 via the limbs 46 into therelease position shown in FIG. 2. In this respect, the bolts 34 aredisplaced in the direction of the cover interior, that is they are movedinto their release position.

Each bolt spring 36 in this respect has such large dimensions that itsspring force is sufficient to displace the slider 50 into its releaseposition on its own and simultaneously to pull the respective other bolt34 via the linkage into its release position. If therefore the boltspring 36 a of the one bolt 34 a fails because it has broken, forexample, the slider 50 and the bolt 34 a as well as the bolt 34 b arenevertheless displaced into the release position by the bolt spring 36 bof the other bolt 34 b. It is therefore ensured that the cover 30 isalso reliably released in the simple defect case, that is when one ofthe bolt springs 36 fails.

A sectional view of the cover along a line A-A indicated in FIG. 2 isshown in FIG. 3. A damping pin 90 provided for holding the satellite inthe ejection direction is preloaded with respect to the satellite by adamping pin spring 92 in the closed position of the cover 30. Thedamping pin spring 92 is in this respect supported at a clamping screw94 that is fixedly connected to the cover frame 32.

One of the lever bearing pins 72 is additionally visible in FIG. 3 androtatably supports the corresponding rocker lever 64 via a lever bearingsleeve 73. Furthermore, one of the rotational pins 76 is visible thatsupports the associated magnetic plate 74 rotatably with respect to thecorresponding rocker lever 64.

FIG. 5 shows a sectional view of a corner region of the cover 30 in theblocking position. The bolt 34 in this respect projects laterally out ofthe cover frame 32 and is in engagement with a counter-bearing element100 fastened to the frame 22 for blocking the cover 30 in the closedposition. The bolt spring 36 in this respect preloads the bolt 34 intothe release position. The bolt 34 has at its end projecting from thecover frame 32 a slope 96 that contacts a ball bearing 18 that isfastened to the counter-bearing element 100. The slope 96 has a sweptcontour. The bolt 34 can be drawn particularly smoothly into theinterior of the cover 30, that is into its release position, due to theslope 96 and due to the ball bearing 98. In this respect, the slope 96can slide off at an outer ring of the ball bearing 98 without the bolt34 being blocked. In particular since the outer ring of the ball bearing98 is rotatable with respect to the counter-bearing element 100, gallingbetween the bolt 34 and the counter-bearing element 100 is also avoidedat high loads. A reliable drawing in of the bolt 34 is therefore ensuredwith a particularly high reliability.

The damping pin springs 92 of which one is shown in FIG. 3 and the coverspring 26 are each per se and at least together of sufficiently largedimensions that the bolt 34 is preloaded in the closed position of thecover with the slope 96 so much against the ball bearing 98 that bothbolts 34 are themselves displaced inwardly, that is into their releasepositions, via the respective slopes 96 if both bolt springs 36 fail. Afurther redundancy factor is hereby provided that ensures with aparticularly high reliability that the bolts 34 are displaced into therelease position at the desired time and release the cover 30 to ejectthe satellite.

FIG. 6 shows an alternative embodiment of a cover 30′ that covers two ofthe four satellite chambers in the ejection unit 20 of FIG. 1.Alternatively, for example, two of the adjacent satellite chambers canbe connected to form a wider satellite chamber for a wider satellite andcan be closed by the cover 30′. The cover 30′ just like the cover 30 ofFIGS. 1 to 5 has a release mechanism for moving two bolts 34 a′ and 34b′ into a release position. The release mechanism is, however, coveredby a cover covering 102 in FIG. 6. The cover 30′ therefore substantiallycorresponds to the cover 30 of FIGS. 1 to 4, but is wider.

In FIGS. 7 to 9, the fixing apparatus 150 of the ejection unit 20 ofFIG. 1 is shown in a perspective view and in side views respectively.The fixing apparatus 150 comprises a plurality of pairs of fixingelements 152 that each act in a common plane and that are eachdisplaceable in a translatory manner transversely to the ejectiondirection A to fix or release the satellite. The fixing apparatus 150additionally comprises a hollow section 156 and a control bar 166 thatextends through the hollow section 156 and is displaceable relativethereto along the ejection direction A. The control bar 166 is coupledvia a pivot pin 172 to a coupling member 170 rotatable about the pivotpin 172. The coupling member 170 is, as shown in FIG. 1, coupled at anend disposed opposite the pivot pin 172 to the associated cover 30 suchthat an opening of the cover 30 displaces the control bar 166 along theejection direction A, to the right in FIGS. 7 to 9, in the direction ofa release position. The control bar 166 is guided by a sleeve 168 in acover-side end region.

A support element 178 is provided that is fixed to the frame 22 anddisplaceably guides the control bar 166. A spring 180 that preloads thehollow section 156 in the ejection direction A via a disk 182 issupported at the support element 178. In the closed position of thecover, a spring 174 additionally preloads the hollow section via asecuring ring 175 with respect to the control bar 166 and against theejection direction A. A disk 175 is arranged between the hollow section156 and the spring 174 and is displaceably supported in a cut-out of thecontrol bar 166, wherein the cut-out is long enough in the axialdirection, that is along the ejection direction A, that the spring 174can balance production tolerances, for example minimal size differencesof satellites.

If the control bar 166 is now displaced through an opening of the coverin the ejection direction A, the spring 174 first relaxes and the disk176 moves, after a short opening distance, into engagement with anabutment of the cut-out of the control bar 166 at the side of theejection spring. The spring 180 thereupon displaces the hollow section156 in the ejection direction A via the disk 182. The displacement ofthe hollow section 156 effects a movement of the fixing elements 152 outof a fixing position into a release position, which will be explained inmore detail below, in particular with respect to FIG. 12.

A securing ring 184 is furthermore fastened to the control bar 166 andthe hollow section 156 has a cut-out 185 corresponding to the securingring 184 with an abutment 183 at the cover side. When the securing ring184 comes into engagement with the abutment 183 on the displacement ofthe control bar 166 in the ejection direction A, the hollow section 156is displaced with the control bar 166 in the ejection direction A. Aredundant measure is thus realized by which the hollow section 156 isalso displaced into the release position when the spring 180 fails. Thesatellite is therefore released at the desired ejection site with aparticularly high reliability.

A latch 186 that is supported in a floating manner with respect to thecontrol bar 166 is provided at an end of the control bar 166 at theejection spring side. The latch 186 is preloaded with respect to thecontrol bar 166 against the ejection direction A by a spring 194,wherein the spring 194 is supported at a securing ring 196 of thecontrol bar 166. The latch 186 is displaceably guided with respect tothe control bar 166. The control bar 166 has a guide pin 190 that isguided in a linear guide 192 of the latch 186. As soon as the guide pin190 abuts an end of the guide 192 at the cover side, the latch 186 isdisplaced together with the control bar 166 in the ejection direction Aand a latch pin 188 is moved into a release position. This process willbe described in more detail below with reference to FIG. 13.

The latch 186 and the coupling member 170 can be attached to the controlbar 166 in different orientations. Depending on the installationposition of the fixing apparatus 150 in the ejection unit 20, the latch186 in accordance with FIG. 8 or in accordance with FIG. 9 cantherefore, for example, be fastened to the control bar 166. Differentpossible orientations of the coupling member 170 are indicated in FIG.9.

In FIGS. 10 and 11, the fixing apparatus 150 is shown together with arail 162 for the satellite in different perspective views. The rail 162has a plurality of transverse guides 164 in each case for a fixingprojection 153 of a fixing element 152. It can also be seen in FIG. 11that the rail 162 forms a guide in the ejection apparatus A for thelatch 186. The coupling member 170, the support element 178 and thelatch 168 with the latch pin 188 are furthermore in particular visiblein FIGS. 10 and 11.

FIG. 12 shows one of the fixing elements 152 in detail in a sectionalview. The fixing element 152 comprises a slot guide 154 that is inengagement with two guide rollers 160 that are carried by respectiveguide pins 158. The guide pins 158 are fastened to a projection 157 ofthe hollow section 156. The fixing element 152 additionally comprises afixing projection 153 for acting on the satellite, wherein the fixingprojection 153 is guided in a transverse guide 164 of the rail 162transversely to the ejection direction A.

The slot guide 154 is formed as an elongate hole that extends obliquelywith respect to the ejection direction A. When the hollow section 156 isdisplaced relative to the rail 162, to the right in FIG. 12, the guidepins 158 and the guide roller 160 cooperate with the slot guide 154 suchthat the fixing element 152 is displaced along the transverse guide 164with respect to the satellite, that is downwardly in FIG. 12. If, incontrast, the hollow section 156 is displaced in the ejection directionA, that is to the left in FIG. 12, the fixing element 152 is moved intoa release position, that is, is displaced upwardly in FIG. 12.

A satellite platform 220 is shown in FIG. 13 that is preloaded in theejection direction A by an ejection spring, not shown. The satelliteplatform 220 is secured by a lever 224 that engages into a securingcut-out 222. The lever 224 is rotatably supported by a pivot bearing 226and is preloaded by a spring 228 into a released position with respectto the pivot bearing 226 with regard to the securing cut-out 222. Thelatch pin 188 holds the lever 224 in a secured position, that is inengagement with the securing cut-out 222, against the spring force ofsaid spring 228.

When the latch 186 is displaced in the ejection direction A, the latchpin 188 moves out of engagement with the lever 224 and releases it intothe released position such that the ejection spring can displace thesatellite platform 230 in the ejection direction A and thus ejects thesatellite. If the lever 224 is in the released position, a movement ofthe latch 186 against the ejection direction A, that is to the left inFIG. 13, can produce a collision of the latch pin 188 with the lever224. This can, for example, be caused by an accidental closing of thecover 30 during an assembly or handling of the ejection unit 20. Sincethe latch 186 is supported in a floating manner with respect to thecontrol bar 166, the latch 186 can simply be cushioned toward the spring194 and the securing ring 196 in the case of a collision and damage, inparticular to the lever 224, is avoided.

The ejection unit 20 of FIG. 1 is configured such that the fixingelements 152 are moved into their release position, that is release thesatellite, at an opening angle of the associated cover 30 ofapproximately 90°. At an opening angle of approximately 105°, the latch186 is moved into its release position and thus releases the ejectionspring for ejecting the satellite. This temporal sequence is inparticular implemented by the above-described mechanisms.

The ejection unit 20 can receive a satellite of the size 3 U inaccordance with the CubeSat standard in the configuration shown, forexample in one of the four satellite chambers. Alternatively, forexample, a satellite of the size 1 U and one of the size 2 U can also bereceived together, for example, in a satellite chamber. It is alsopossible to place adjacent chambers together, that is, for example, toremove provided partition walls between the chambers in order, forexample, to provide a chamber for a satellite of the size 6 U. Such achamber can in particular be closed by a cover 30′ in accordance withFIG. 6.

A covering 250 of the ejection unit 20 of FIG. 1 is shown in a plan viewand a side view respectively in FIGS. 14 and 15. The covering isfastened to the frame 22 of the ejection unit 20 by screws 252 to coveran opening of the frame. A respective screw 252 has a screw head havinga cylindrical section 254 and a peripheral projection 256. An elasticlug 258 engages about the cylindrical section 254 with a correspondingcut-out and preloads the screw 252 via the peripheral projection 256 ina fastening direction, downwardly in FIG. 15. The lug 258 is fastened tothe covering 250 by screws 260. The screw 252 has an internal drive, inthis embodiment a hexagon socket.

To release the covering 250 from the frame 22, the screws 252 can beunscrewed, wherein they remain preloaded in the fastening direction bythe lug 258. The respective screw 252 is also hereby held at thecovering 250 in the released state such that the screw 252 is not lost.

REFERENCE NUMERAL LIST

-   20 ejection unit-   22 frame-   24 cover axis-   26 cover spring-   30, 30′ cover-   32 cover frame-   34 a, b bolt-   36 a, b bolt spring-   38 securing ring-   40 disk-   42 bolt head-   44 joint pin-   46 limb-   47 joint pin-   48 elbow element-   50 slider-   51 joint pin-   52 pivot arm-   53 slope-   54 slider spring-   56 spring guiding pin-   58 first slider bearing-   60 second slider bearing-   62 spring-   64 a, b rocker lever-   66 pin-   68 ball bearing-   70 lever spring-   72 lever bearing pin-   73 lever bearing sleeve-   74 magnetic plate-   76 rotational pin-   78 magnet-   80 abutment-   82 spring-   84 a, b circuit board-   86 screw-   88 cable conduit-   90 damping pin-   92 damping pin spring-   94 clamping screw-   96 slope-   98 ball bearing-   100 ball bearing element-   102 cover covering-   150 fixing apparatus-   152 fixing element-   153 fixing projection-   154 slot guide-   156 hollow section-   157 projection-   158 guide pin-   160 guide roller-   162 rail-   164 transverse guide-   166 control bar-   168 sleeve-   170 coupling member-   172 joint pin-   174 spring-   175 securing ring-   176 disk-   178 support element-   180 spring-   182 disk-   183 abutment-   184 securing ring-   185 cut-out-   186 latch-   188 latch pin-   190 guide pin-   192 guide-   194 spring-   196 securing ring-   220 satellite platform-   222 securing cut-out-   224 lever-   226 pivot bearing-   228 spring-   250 covering-   252 screw-   254 cylindrical section-   256 projection-   258 lug-   260 screw-   A ejection direction

1. An ejection unit for at least one satellite, the ejection unit comprising a frame that defines an inner space for receiving the satellite; and a retention device for holding the satellite in the inner space, the retention device being configured such that the satellite is releasable by the retention device.
 2. The ejection unit in accordance with claim 1, wherein the retention device comprises a cover for closing the inner space, with the cover being blocked in a closed position by at least one shiftable bolt in a releasable manner with respect to the frame.
 3. The ejection unit in accordance with claim 2, wherein the bolt is formed as part of the cover.
 4. The ejection unit in accordance with claim 2, further comprising a release mechanism by which the bolt is movable from a blocking position into a release position.
 5. The ejection unit in accordance with claim 4, wherein the release mechanism comprises a slider coupled to the bolt, the slider being held preloaded in a blocking position and being releasable therefrom to shift the bolt into a release position.
 6. The ejection unit in accordance with claim 5, wherein the bolt is connected by a linkage in an articulated manner to the slider, with the slider and the linkage forming an elbow joint for the bolt.
 7. The ejection unit in accordance with claim 2, wherein two bolts are provided.
 8. The ejection unit in accordance with claim 7, wherein each bolt is preloaded by a spring in the direction of a release position, with the bolt being set force free in a blocking position by a linkage.
 9. The ejection unit in accordance with claim 7, wherein each bolt is connected via a separate linkage to a slider of the release mechanism and the linkages form a double elbow joint with the slider, the double elbow joint coupling the bolts to the slider such that a movement of a bolt into the release position results in a movement of the other bolt into the release position.
 10. The ejection unit in accordance with claim 2, wherein the release mechanism comprises at least one rocker lever by which the at least one bolt is held in a blocking position.
 11. The ejection unit in accordance with claim 10, wherein two rocker levers are provided and a preloaded element of the release mechanism comprises a pivot arm that is in the blocking position in engagement with both rocker levers for supporting the preloaded element, with the pivot arm being pivotable such that the preloaded element can be released out of the blocking position by tilting only one rocker lever into a release position.
 12. The ejection unit in accordance with claim 10, wherein the at least one rocker lever has a pivot bearing and is loaded by a pretensioned element of the release mechanism that has a slope by which a force exerted on the rocker lever by the pretensioned element extends in the direction of the pivot bearing.
 13. The ejection unit in accordance with claim 2, wherein the bolt has a slope for running onto frame side a counter-bearing for the bolt in the blocking position.
 14. The ejection unit in accordance with claim 13, wherein the counter-bearing is a ball bearing.
 15. The ejection unit in accordance with claim 13, wherein in a blocking position the bolt and the counter-bearing are pretensioned against each other in an ejection direction.
 16. The ejection unit in accordance with claim 2, wherein two bolts and two rocker levers of the release mechanism are arranged symmetrically with respect to a slider of the release mechanism.
 17. The ejection unit in accordance with claim 1, wherein the ejection unit defines an ejection direction and the retention device comprises a fixing apparatus that engages at the satellite for fixing the satellite transversely to the ejection direction, wherein the fixing apparatus has at least one movable fixing element that is movable in a translatory manner between a fixing position and a release position.
 18. The ejection unit in accordance with claim 17, wherein at least a pair of fixing elements is provided that are active in a common plane that extends transversely to the ejection direction.
 19. The ejection unit in accordance with claim 17, wherein a plurality of fixing elements or pairs of fixing elements are provided that are arranged distributed along the ejection direction.
 20. The ejection unit in accordance with claim 17, wherein a spring element is provided that clamps the or each fixing element in the fixing position against the satellite.
 21. The ejection unit in accordance with claim 17, wherein the fixing apparatus has a guide for the fixing element by which the fixing element is movable between the fixing position and the release position.
 22. The ejection unit in accordance with claim 17, wherein the fixing element is displaceably supported in a rail for the satellite and/or for a satellite platform.
 23. The ejection unit in accordance with claim 17, wherein the fixing apparatus is coupled to a cover of the ejection unit such that an opening of the cover effects a moving of the or each fixing element into the release position.
 24. The ejection unit in accordance with claim 17, wherein the fixing apparatus comprises at least two elements that are displaceable relative to one another along the ejection direction for fixing and/or releasing the satellite.
 25. The ejection unit in accordance with claim 24, wherein one of the elements is configured as a hollow section and a control bar is provided for controlling the displacement of the element relative to the other element, the control bar extending through the hollow section.
 26. The ejection unit in accordance with claim 1, further comprising an ejection spring blockable by means of a lever and a latch for locking the lever in a blocking position, with the latch being coupled to a cover of the ejection unit supported in a floating manner.
 27. The ejection unit in accordance with claim 26, wherein the latch is coupled to the cover via a spring. 